​🧑‍💻​ C - Stacks, Queues - LIFO, FIFO

Learning Objectives

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At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

• What do LIFO and FIFO mean
• What is a stack, and when to use it
• What is a queue, and when to use it
• What are the common implementations of stacks and queues
• What are the most common use cases of stacks and queues
• What is the proper way to use global variables

Requirements

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General

• Allowed editors: vi, vim, emacs
• All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89.
• All your files should end with a new line.
• A README.md file, at the root of the folder of the project is mandatory.
• Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl
• You allowed to use a maximum of one global variable.
• No more than 5 functions per file.
• You are allowed to use the C standard library.
• The prototypes of all your functions should be included in your header file called monty.h.
• All your header files should be include guarded

More Info

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Data Structures

    /**
     * struct stack_s - doubly linked list representation of a stack (or queue)
     * @n: integer
     * @prev: points to the previous element of the stack (or queue)
     * @next: points to the next element of the stack (or queue)
     *
     * Description: doubly linked list node structure
     * for stack, queues, LIFO, FIFO
     */
    typedef struct stack_s
    {
            int n;
            struct stack_s *prev;
            struct stack_s *next;
    } stack_t;

/**
 * struct instruction_s - opcode and its function
 * @opcode: the opcode
 * @f: function to handle the opcode
 *
 * Description: opcode and its function
 * for stack, queues, LIFO, FIFO
 */
typedef struct instruction_s
{
        char *opcode;
        void (*f)(stack_t **stack, unsigned int line_number);
} instruction_t;

Compilation & Output

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The code will be compiled this way:

$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o monty

• Any output must be printed on stdout
• Any error message must be printed on stderr

​💥​ The Monty language

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Monty 0.98 is a scripting language that is first compiled into Monty byte codes (Just like Python). It relies on a unique stack, with specific instructions to manipulate it. The goal of this project is to create an interpreter for Monty ByteCodes files.

Monty byte code files

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Files containing Monty byte codes usually have the .m extension. Most of the industry uses this standard but it is not required by the specification of the language. There is not more than one instruction per line. There can be any number of spaces before or after the opcode and its argument:

group_luis_carlos@ubuntu:~/monty$ cat -e bytecodes/000.m
push 0$
push 1$
push 2$
  push 3$
                   pall    $
push 4$
    push 5    $
      push    6        $
pall$
group_luis_carlos@ubuntu:~/monty$

Monty byte code files can contain blank lines (empty or made of spaces only, and any additional text after the opcode or its required argument is not taken into account:

group_luis_carlos@ubuntu:~/monty$ cat -e bytecodes/001.m
push 0 Push 0 onto the stack$
push 1 Push 1 onto the stack$
$
push 2$
  push 3$
                   pall    $
$
$
                           $
push 4$
$
    push 5    $
      push    6        $
$
pall This is the end of our program. Monty is awesome!$
group_luis_carlos@ubuntu:~/monty$

The monty program

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• Usage: monty file
  • where file is the path to the file containing Monty byte code.
• If the user does not give any file or more than one argument to your program, print the error message USAGE: monty file, followed by a new line, and exit with the status EXIT_FAILURE.
• If, for any reason, it’s not possible to open the file, print the error message Error: Can't open file <file>, followed by a new line, and exit with the status EXIT_FAILURE
  • where <file> is the name of the file.
• If the file contains an invalid instruction, print the error message L<line_number>: unknown instruction <opcode>, followed by a new line, and exit with the status EXIT_FAILURE.
  • Where is the line number where the instruction appears.
  • Line numbers always start at 1.
• The monty program runs the bytecodes line by line and stop if either:
  • it executed properly every line of the file
  • it finds an error in the file
  • an error occured
• If you can’t malloc anymore, print the error message Error: malloc failed, followed by a new line, and exit with status EXIT_FAILURE.
• You have to use malloc and free and are not allowed to use any other function from man malloc (realloc, calloc, …)

Opcodes

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Opcode	Description
push	The opcode push pushes an element to the stack.
pall	The opcode pall prints all the values on the stack, starting from the top of the stack.
pint	The opcode pint prints the value at the top of the stack, followed by a new line.
pop	The opcode pop removes the top element of the stack.
swap	The opcode swap swaps the top two elements of the stack.
add	The opcode add adds the top two elements of the stack.
nop	The opcode nop doesn’t do anything.
sub	The opcode sub subtracts the top element of the stack from the second top element of the stack.
div	The opcode div divides the second top element of the stack by the top element of the stack.
mul	The opcode mul multiplies the second top element of the stack with the top element of the stack.
mod	The opcode mod computes the rest of the division of the second top element of the stack by the top element of the stack.
pchar	The opcode pchar prints the char at the top of the stack, followed by a new line.
pstr	The opcode pstr prints the string starting at the top of the stack, followed by a new line.
rotl	The opcode rotl rotates the stack to the top.
rotr	The opcode rotr rotates the stack to the bottom.
stack	The opcode stack sets the format of the data to a stack (LIFO). This is the default behavior of the program.
queue	The opcode queue sets the format of the data to a queue (FIFO).

🧑‍💼​ PROJECT FILES

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Files	Description
main.c	Main function and check_blank function,
monty.h	Header of function prototypes.
functions-0.c	Functions like: command_builder and m_com (comments)
choose_option.c	Functions like: m_push, m_pall, execute_ops and freell.
choose_option_2.c	Functions like: mega_pint, m_pop, m_swap, m_add, m_nop.
choose_option_3.c	Functions like: m_sub, m_div, m_mul, m_mod, m_pchar.
choose_option_4.c	Functions like: m_pstr, isint, m_rotl, m_rotr, m_queue
choose_option_5.c	Functions like: m_stack, m_pushq

🧠​ Brainf*ck script

Brainfuck is an esoteric programming language created in 1993 by Urban Müller.

Notable for its extreme minimalism, the language consists of only eight simple commands, a data pointer and an instruction pointer. While it is fully Turing complete, it is not intended for practical use, but to challenge and amuse programmers.

Brainf*ck simply requires one to break commands into microscopic steps.

The language's name is a reference to the slang term brainfuck, which refers to things so complicated or unusual that they exceed the limits of one's understanding.

You can install the bf interpreter to test your code: sudo apt-get install bf

This script is in bf folder.

Scripts

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Files	Description
1000-school.bf	Write a Brainf*ck script that prints School, followed by a new line
1001-add.bf	Add two digits given by the user.
1002-mul.bf	Multiply two digits given by the user.
1003-mul.bf	Read the two digits from stdin, multiply them, and print the result, followed by a new line.

Authors

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• Carlos Soria - Soria-c

• Luis Manrique - luismch158158